Process of preparing cyanogen compounds.



J. E. BUGHER.

' PROCESS OF PREPARING GYANOGBN COMPOUNDS.

APPLICATION FILED DEO.18, 1'912.

Patented Apr. 28, 1914.

VAW/A% eusr LAMP EXHAUST -.?WI TNESSES: INVENTOR. $5 d 61 ATTORNEY.

aspects, tobe regarded as an impro uement ,To all whom it may concernJOHN E. nuonnajor co'iznntriii, rtr'ippn' rsniiiin sssrqnbitl roniixrnoonn rnon- UCTS COMPANY. A CORPORATION OF RHODE ISLAND.

rnocnss or PREPARING oYANooEN comrounns.

Specification of Letters ratent.

se -issuance, 1914.

Application filed December 18,1912. Serial No. 737,368.

' Be it known that I, JOHN E, -BUCHER,1QiE Coventry, in the county ofKent and State of Rhode Island, haveinvented certain .new

i and useful Improgements inthe-Process of Preparing Cyanogen.Compounds, of which the following. is a specification.,:

nitrogen and more particularly t'o an vimproved process of preparing, ifdesired,-subr .stantially pure cyanogen compounds and derivativestherefrom, together with alu,- able by-products incident totheproduction of such a compound or compounds.

The present processes, in certain ofits upon the processes described inmy pending applications forlU. S Letters Patent, respectively designatedSerial ,No. 711,211, filed July 24, 1912, and Serial No. 726,924,filedOctober 21, 1912. a v 1 One of the features of importance involvedin the present process is the utilization of distillation broadly andparticularly of distillation under diminished pressure as a means forfacilitating the .production or preparation of pure or substantiallypure cyanogen compounds, e. g. sodium cyanid. Such procedure is of verygreat importance whenused in connection with the synthetic formation ofcyanids and the like asset forth at length in my said pendingapplications, and especially in that designated Serial No, 726,924. Insaid application I have intimatedthat distillation of cyanid fromthe'reactive mass containing catalytic material is feasible and I hereindescribe more particularly an advantageous way of effecting suchdistillation. While this, op} eration is of particular value inconnection with my said previously described processes, I do not wish tobe limited thereto, except where in certain of the appended claims Ispecifically include as steps in the process certain of those moreparticularly set forth in said pending applications; since I am awarethat the distillation of cyanids in the manner hereinafter described notonly facilitatesthe production of such-substances in a form in whichthey are substantially immediately ready for use without furthertreatment, but further is of value ineffecting a purification of cyanidsproduced by other methods than those described in,.my said applications;so that it may even be fication, of cyanogen compounds in e ph- I .1calsense, but, it may', in addition, also e ect ThiS lIlVQDtlOIirelatesto the fixation of.

some oflt'h'e vvery impure. commerclal cyanlds produced ,byknown'processes, e. g .-from nitrogenousmaterials such as bitummous coalor the like. .The present process, theref0re,-not only effects theripu-rification accompanied by chemical reactions.

T I have found mystudyof theart that with. but few; importantexceptions, cyanids havebeenobtained by lixiviating the crudefurnace-products, in which they-are formed, with water; by absorbingcyanogen or hydrocyanic acid in {aqueous valkaline solu drained ofi. inthe moltencondition seem to be those usin ammonia rather thanfrecnitrogen'fon t e production of the cyanids.

The above -methods of purification depending upon lixiviation andcrystallization are open to many serious objections, such as the,poisonous properties of cyanogen compounds, thew decomposition of thecyanids in..water solution, expense, the sparing solubility of cyanidsin alcohol, inflammability of the alcohol, etc. In some cases thelixiviation results in a loss of alkali; and, in substantially any casethe reaction products must be allowed to cool before they can belixiviated. .Also the moist residue from lixiviation must in certaincases be freed from water before it can again be used for thepreparation of another quantity of cyanid, because water will reactdeleteriously when materials such as potassium, sodium, or lithium,which maybe directly concerned inthe reaction in question, are used. Itmay also injure, or indeed in some cases render wholly useless many ofthe catalytiomaterials"available for use, e. 9. magnesium, lithium,calcium, certain nitrids, etc. v

The foregoing and other objects of my invention, will be hereinafterreferred to and the novel process and steps in said process whereby thesame may be attained will be more particularly set forth in the appendedclaims 1 Y I am aware that various modifications and changes may be madein my process and the manner of conducting the same, without departingfrom the spirit of my invention and hence desire to be limited only bythe scope of said claims considered broadly in t e light of mydisclosure.

In the accompanying drawing which forms a part hereof and in which likereference characters designate like parts throughout the several vlews,I'have exem plified an apparatus ation of my process, but it will beunderstood that I am not to be limited in any way .to thisexemplification since various other forms and types of apparatus arewell adapted to the process in question. Referring to the drawing:Figure 1 1s a longitudinal vertical section of a muflle furnace withretorts in position-therein. Fig. 2 is an end velevation of saidfurnace, the blast lamp being omitted for convenience of illustration.Fig. 3 is a fragmentar section taken on line III-III of Fig. 1. ig. 4 isa similar section of a retort adapted for the use of air in the process.Brickwork or other suitable material may be employed in the constructionof the mufile 1, and one or more pipes 2, serving as retorts, Couplingsor unions 3, serve to connect the ends of the retorts, or the extensions2 of the same, hereinafter referred to, to the pipes 45; thosedesignated 4 being the pipes for supplying nitrogen or air, as the casemay be. The gases, notably carbon monoxid, evolved during the operationof the process are conveyed away via pipes 5-5. A blast lamp 6, or othersuitable source of heat may be disposed in the preferably open end ofthe muflle, and this apparatus should, of course, be capable of heatingthe retorts up to the reaction temperatures employed.

Assuming that the process is to be conducted in such fashion as topermit the use of air, the latter is led in through pipes 4 andpreferably first encounters one or more masses 7 of charcoal or othersuitable oxygen consuming' material. These masses preferablysubstantially fill the pipes at the points where they are disposed sothat all of the air is obliged to pass therethrough. I prefer tointerpose wire auze spacing or supporting screens 8, or he like, betweenthe charcoal and the body of the reaction mixture 9 which is nextencountered by the gases flowing through the pipe or retort; since it isdesirable to keep the charcoal away from the charge.

During the course of the operation, the alkali metal will be evolved inthe manner hereinafter described, and if the charcoal is in contactwiththe reactive mass or mixture, it may, by capillary action, or from anyother cause, remove a portion of such suitable for the efi'ectu-,

may extend directly therethrough.-

alkali metal from. reduce the yield.

The mixture 9 preferabl consists of pulverulent coke, graphite, carcoal, coal, or the like, very intimately mixed with finely dividedcatalytic material, e. 9. iron, and sodium carbonate or otherinexpensive source of the metal forming the base of the cyanogencompound sought, or to be incidentally formed durin the operation.

If nitrogen be used instead of air, the charcoal screens or masses 7may, of course, be omitted. The extensions or pipes 2 may be coupleddirect to the exit ends of the respective retorts by couplings or unions3, and to the pipes 5 by couplings 3, in such manner as to beindividually readily removable therefrom without disturbing theremaining parts of the a paratus. Each of the pipes 5 is connected y apipe 10 with a pipe 11 leading to anexhaust pump 12, or other suitabledevice by means of which a vacuum or partial vacuum can be created inthe retorts; the several sets of valves 13, l4 and 15 providing meansfor preventing an influx of air or other gas into the articular retortor retorts in which it is desired to effect a reduction of pressurebelow that of the atmos here. Thus, after the formation of a su cientyield of cyanid in the reactive masses 9 has been effected, valves 13and 15 will be closed and those designated 14. will be opened; theexhaust pump, of course, bein in operation. The cyanid will distil out othe masses 9, at the temperature of the operation, and will condense inthe extended and relatively cool tubes 2, depositing as a clear liquidwhich solidifies into glass-like masses or lumps. It may even be cast inmolds to form sticks of substantially pure cyanid. When sufiicientcyanid has been obtained in this manner, the blast lamp may be shut off,the valves 14 closed and the tubes or sections 2 removed, separately ifdesired, by loosening the couplings at the respective ends thereof.

The retorts and condensing tubes may be made-of any suitable materialbut it is important in this connection to consider the role .whichcertain-substances, such as iron are adapted to play under conditions towhich I shall refer, in decomposing cyanogen compounds, e. g. sodiumcyanid; iron, for example by reason of its ability, at a relatively hightemperature, to absorb or separate carbonfrom such compounds. Failure tonote this phenomenon possibly explains the failure of certain knownprocsaid mass and thereby esses having for their object the syntheticproduction, or the purification, of cyanids.

The action of a material capable of dissociating the cyanogen radical isexemplified in the following equation (1) 2KCN+iron=2K+carburizediron+N,.

In said application, Serial Number 726,924, I have shown thatquantitative'yields of alkali cyanids can be obtained by heating alkalicarbonates with iron and carbon in a current of nitrogen underconditions which I shall herein briefly review, and since, in view ofthe foregoing equation, it is possible to heat cyanid with carbon-freeiron so as to effect a quantitative decomposition of the cyanid, itfollows, conversely, that when the iron is sufliciently carburized, nodecomposition should take place. Pursuant to this, I have found thatsodium cyanid as well as potassium cyanid can be distilled readily,

, even at atmospheric pressure, and without sensible decomposition, inreceptacles composed of sufficiently carburized iron, which materialisprincipally of value on account of its cheapness as well as itsdurability, and ability to withstand the temperatures at which theoperation can be conveniently conducted. It is possible to effect thecyanid distillation in vessels of hard glass, quartz, or the like; whileiron apparatus lined with a substance not capable of decomposing alkalicyanids, e. 9. copper, may also, of course, be used for the distillationof the alkali cyanids under diminished pressure. If iron apparatus beused, the iron parts subject to contact with the hot cyanid vapors orliquid will in time become sufliciently carburized by the action of thecyanid itself, after which the distillation may be advantageouslyconducted in such apparatus. Considering next the reactive materialsused in the process, the manner of disposing them in the retort orretorts, and the reactions which take place therebetween, I may cite,preliminarily, the following equation, taken from my said application,berial Number 7 26,924.

(2) 2Na+2C+N +iron:2NaCN+iron.

This equation is, it will be observed, practically the reverse ofequation 1;-the direction of the reaction depending upon the activemasses of materials involved and conditions of temperature, etc. That itis possible to effect the formation of alkali cyanids synthetically fromcompounds of the metal, 6. g, sodium, forming the base of the cyanogencompound to be produced,-is also shown by my disclosure in "saidapplication wherein certain experiments are set forth at length, theresults of which demonstrate that from about 700 C. (roughly)substantially up to the eutectic point of the carbon dissolvingcatalytic material, alkali cyanids may be produced from, for example,alkali carbonates, hydrates, or the like, free nitrogen and carbon,through the instrumentality or intermediacy of said catalytic materialwhile the latter is in solid form.

The preferred catalytic material is iron which is a most efficientsolvent for carbon; and the preferred form of this catalytic material isthe one exjposing the'greatest practicable catalytic solution surfacecompared to the volume of said material, 7?. e. finely pulverulent. ,Ialso set forth at length in my last mentioned application thedesirability of not only providing such an enormously extended solutionsurface, but further the advantages of maintaining said surface,both asregards the maintenance of an adequate supply of carbon in solutiontherein and further as to the physical maintenance of said surface byconducting the operation, where a solid catalyzer was employed, attemperatures materially below the'eutectic point of said material whencontaining preferably substantially its maximum carbon content.

Therein were also shown the advantages of disposing the mass of reactivematerial comprising the alkali metal carbonate (for example), carbon (orcarbonaceous material), and the finely powdered catalyzer, intimatelymixed in such fashion as to not only maintain the carbon supply in thesolution surfaces or surface, but to further provide the requisiteporosity in a suflicient extent of said mass to enable the free nitrogento adequately penetrate thereinto; and to also provide by capillaryaction a relatively enormously extended reactive film surface, thelatter consisting of the alkali metal supplying material, videlicit,liquid sodium carbonate, drawn up (or retained) by the wick like actionof the porous portions of the reactive mass, from the bulk of saidcarbonate held by. gravity in the lower portions of said mass. Ireferred in said case, also, to the desirability of maintaining anadequate supply of nitrogen whereby to facilitate the liberation ofalkali metal vapor from the compound constituting the source of thesame, by reducing the vapor pressure of said metal; the nitrogen currentnot only serving to mechanically remove said vapor but also chemicallyremoving the same by combining therewith and with carbon at the solutionsurface, when said surface was disposed at the place of liberation ofsaid metal.

As I have herein previously indicated, the possibility of cyaniddistillation from the residues of the cyanid forming reaction wereconsidered in said application, and attempted in my comparatively earlywork upon this subject. At atmospheric pressure, however, the boilingpoint of the more commonly used cyanids, e. g. sodium and potassiumcyanids, is for practical purposes relatively too near the eutecticpoint of iron and carbon; so that I found it inexpedient to removeeither of them by distillation from said residues, particularly when thelatter comprised a mixture containing a large excess .of graphite (orthe like) and iron, on account of the melting of the carburized iron. AsI have previously intimated, however, with care, the distillafrom themixture in the retort tion can be made effective even at atmos:

pheric pressure, when conducted in properly carburized iron receptacles.

Even the lowering of the partial vapor pressure by the passageof aconsiderable current of nitrogen, which procedure was at first resortedto uponencountering this difficulty, I found fails to remove the cyanidpractical quantities, at temperatures somewhat point of copper. I solvedthe problem, however, finally as I have already indicated, by subjectingthe cyanid containing residues of the reactive a reduced or diminishedpressure, the distillation being preferably effected directly in andafter the formation of a proper yield of cyanid therein; the diminishedpressure in this receptacle being pro-' duced by means of an eiiicientvacuum or exhaust pump and the retort meanwhile being adequately heated.

The result was extremely satisfactory; the cyaniddistilling out of theiron-graphite mass (iron being the catalytic material, and graphite the.sonrce of carbon, in.this instance) quantitatively at temperatures veryconsiderably below the melting point of copper.

The following experimentimay be given by way of example. A thin coppertube, closed at one end and containing a mixture of sodium cyanid,produced from the action of nitrogen on'sodium carbonate, graphite andiron, was forced into an iron tube. This iron tube was closed at one endand the other end connected with an eflicient. vacuum or exhaust pump.The outer iron tube served to protect the copper from oxidation and alsofrom any tendency to collapse under the effective external pressuredeveloped. The tube was then heated in a furnace to 1020 C. for a shorttime under diminished pressure in the interior thereof.- Upon coolingand opening said tube, it was found that cyanid had distilled from themass, collected as a pool of liquid in the colder part of the tube, andfinally solidified (in this instance) to a mass which was so clear andtransparent that fragments of it could not be told, off hand, fromfragments ofclear glass until water was added. Titration with asolution'of silver nitrate indicated that the specimen contained 99.9per cent. of sodium cyanid and the solution gave no precipitate withcalcium hydroxid. This showed the cyanid to be free from alkalicarbonates and to be substantially chemically pure. This experiment at atemperature below the melting point of copper proves that we can very.easily produce pure cyanid from a mixture of an alkali compound orcompounds, iron and graphite, in a suitable receptacle, by passing acurrent of nitrogen gas over the heated mass; whlle, thereafter, bysimply shutting off the nitrogen and below the melting mass todistillation at without having to tube. The glass opening the connectionto the vacuum pump, the cyanid can be distilled quickly from the hotmass and collected as pure liquid or solid cyanid in a receptaclesuitably conter and found to be so free from alkali compounds that theresulting aqueous solution didnot give any precipitate with silvernitrate or calcium hydroxid nor did it give any Prussian blue test. Itmust hence, have been substantially free from cyanids and carbonates.Moreover, the irongraphite residue left from such a distillation is notcaked and is in excellent condition, as regards the catalytic solutionsurface, to be mixed with another charge of alkali carbonate orcarbonates and used for the production of another portion of the alkalicyanid or cyanids sought. Indeed, it is even possible to admit the newcharge of alkali (metal, carbonate, hydrate or other source of thealkali metal) in a molten or vaporous condition to the iron-carbonmixture in the tube. The process is thus under excellent control, andprovided that a suitable charging and mixing device he provided even thegraphite or carbon charge can be renewed, cool the tube or even toremove its contents. The alkali carbonates may also be distilled underdiminished pressure into the catalytic mixture; thus developing stillfurther the mode of operating the process set forth in my said lastmentioned application wherein it was shown to be practicable to conveythe alkali metal to a relatively remote carbon containing catalyticsurface, either-as a vapor of said metal or as a vapor of a compound ofthe same. I have also distilled the cyanid from the reaction mixture at1000 C; in hard glass tubes sealed at one end and placed in an iron tubelasted long enough for part of the cyanid to distil from the mass.

With the glass I have always obtained considerable metallic sodium,which being more volatile than the cyanid, separated out in liquid formstill further from the heated zone of the tube. This liberation ofsodium is probably due to the contact of the vapor with the iron outeror containing tube, after the glass had partly melted. Sodium was notliberated whencopper tubes. were em-= ployed unless there was someunchanged sodium carbonate present in the charge.

The above cited experiments show that under diminished pressure alkalicyanids can be distilled efficiently from a mass of iron-graphitemixture at temperatures, which I have found may even be below 1000 (3.;and indeed considerably lower in cases where a high vacuum ismaintained. I have also been able to separate the alkali cyanids fromcarbonates, at least partially, by fractional distillation underdiminished pressure. This may be done either in a'copper or carburizediron apparatus, or the like. The process can-also be applied so as toproduce cyanids with both chemical and physical changes combined, as isshown in the following examples. a i v Qyanamids, such as that ofcalcium, may be treated with carbon and salt to form cyanids:

(3) CaCN +C+2NaCl=CaCl +2NaCN' 4. NasCN-l-FezNaON-i-Fes.

The alkali cyanid can then be distilled from the residues of thereaction. Also ferrocyanids and ferricyanids can be heated to formcyanids, thus:

5 KA E(CN) =4KCN+Fe+C,+N,. Simultaneously or later the cyanid formed canbe distilled under a diminished pressure. Also a mixture of sodlumcarbonate, 1ron and graphite and cyanid heated under diminished pressureto distil the cyanid, decomposes in part to yield sodium and carbonmonoxid. a

thus purifying the cyanid.

These examples will serve to illustrate how effectively the method canbe used chemically as well as physically to purify and to preparecyanids.

Referring again to by way of exemplification, it is obvious in view ofthe foregoing that if the charge of graphite or other suitable carbonsupplying material and the carbonate or the like, he in excess,sufiicient yield of cyanid may be effected to warrant the separation ofthe same from the residues of the reaction and from the matter, 6. g.graphite andcarbonate, still unacted upon; such preparation beingeffected in the manner ind cated. Thereafter the exhaust pump may bestopped, the valves 14 closed, and valves 13 and 15 again opened, toresume the formation of cyanid. Thus the stages of the formation andseparation of the cyanid may be alternated, while both steps of theprocess are 'eifectuated in the same piece of apparatus and atsubstantially the same temperature, if desired. I am of the opinion alsothe apparatus given thatthe periodic removal time yanid-sea the reactionresidues is further of'adv ge m so far as the actual formation of theformer 1s concerned,-'sincefif the cyanid is allowed to collect in thereactive mass; the

pores or interstices between the "particles of catalytic material becomeclogged or choked to some measure, the liquid cyanid being drawn up bycapillarity along. withtheiliquid carbonate and, at least, diluting thereactive film of the latter; ifindeed'tlie mass of liquid in a giveninterstice doe's'not' altogether prevent the access'of nitrogen;tbftlieportions of the catalytic solution? surface which constitute the wallsof such interstice.

I have explained at considerable length in my companion application(Serial No. 726,924) the advantage'of maintaining not only anextendedcatalytic solution surface, the carbon present in which; the'ni'trogen supplied by the stream'of the same, and'the alkali metalpresent in or "liberated'fromthe compound ofthe same which constitutesthe source of this metal,"e.'g."sodium carbonate (or the alkali metalsupplied as such), may

react together to form the cyanidibut have also dwelt upon the-'desirabilityof maintaining aconsiderable portion'of this' 'sur facerelatively free from the liquidcarbonate, or the like, so that'thenitrogen and alkali metal may have anopportunity to reach said surface;the latter at 'most', in so far as said portion is concerned,beingcovered merely by a; thin film 'of' the liquid source of the alkalimetal, When such source is used. The alkali metal isfefiicientlyliberated from or adjacent tothis extended -film surface, while theliquid carbonate or like compound used is also vaporized, and this vaporthereafter participates in the re action; either doing so directly, orby first decomposing to liberate alkali metal. The term vapor as used incertain of the ap pended claims is hence to be regarded as of suflicientbreadth to cover both-alkali'metal vapor and that of a compound ofsuchorasimilarly acting metal;-whi1e"the' terxri alkali metal, orcorresponding te'rm,11nle'ss otherwise characterized, is to be regardedas" of sufiicient scope to cover both free'metal and the element, parse,z'.'-e.ias*present, atlfeast initially, in a compound of such imetal.Similar remarks apply to carbon and'to nitrogen, unless these wordsheatherwise qualified in the claims." out the further advantageofremoving-the bulk of the cyanid from said'surfacefor the same reasonthat thebulk'ofthe carbonate, or the like is removed, and also 'fortheu'eason, which I have above indicatedythat' the alkali metalcarbonate, or "the like; win be diluted by the already formed cyanidsothat the production of further cyanid is'retarded. Further, at leastuntil the iron isthoroughly Therein point from the zone of the reaction,

reaction, a certain percentage of the cyanid present in the reactivemass 1s always be ng decomposed, the carbonate or the like beingreformed, to subsequently again be converted to cyanid. By thusremoving'the cyanid therefore, the process as a whole is rendered moreefficient and the production of cyanid per unitof time, expedited.

The application of cyanid particularly at reduced pressure, to my formerprocess is therefore extremely beneficial from anumber ofstandpoints,not the least important of which is the rendering possi ble of theeconomical separation of the cyanid from the reactive mass at suchtemperatures as to permit of the use commercially of copper or of highlycarburized llOIl apparatus, thedistillatlon being efi'ected, withoutundue care, at temperatures below the eutectic point of the latter. Itobvlates lixiviation with its consequent impairment (temporary orpermanent) of the efiiciency of'the reactive residue, and it obviatesthe necessity, where lixiviationis resorted to, of evaporating OH orotherwise removlng the water which holds the so removed cyanld insolution. It also renders possible the efiidistillation,

cient use of such catalytic agents (in lieu of the iron) as magnesium orlithium, because with these latter lixiviation cannot well be employedowing to the action of water thereon. The separation of cyanid from theresidues ofthe reaction, by distillation (particularly in 'vcwuo) alsomakes practical the preparation of ammonia from sodium cyanid throughthe cyanate according to the equation:

(7) NaCN+air=NaCNO+nitrogen. (8) 2NaONO+3H,O=

Na,CO +NH,+CO

Here, it is to be noted that the process yields far more nitrogen,equation than it can use, also ammonia and carbon dloxid are obtainedaccording to equation 8. The latter substances are exactly what isrequired for the ammonia soda process or for making certain amid-likefertilizers. These two reactions are each-practically instantaneous andafford a means ofgetting ammonia from cyanids without the greatdisadvantage of oxidation of the iron or carbon b steam or air, thedecomposition of ammoma at a red heat, the slower action of steam atlower temperatures, or the formation of cyanogen to contaminate theammonia.

As the nitrogen may be conveniently sup plied under a pressure abovethat of the atmosphere, in certain of the appended claims the wordsunder a pressure below that at which said compound was formed are obviously of sufiicient'breadth to not only cover distillation, or thelike, at a pressure below that of the atmosphere, but also to coverabove atmospheric pressure provided that the cyanogen compound stillhigher pressure.

Having thus described my invention what I claim is was formed at a 1.The process of fixing atmospheric nItro gen which comprises efl'ectin' areaction in which an initially combine alkali metal, initially freenitrogen and dissolved carbon participate to form a cyano en compound, ybringing the molecules 0 nitrogen into contact with the dissolved carbonpresent in an extended catalytic solution surface, while the materialwith which they are combined, in the vicinity of said solution surfaceand distilling under reduced pressure the so formed cyanid from residuesof said reaction.

2. The process of producing substantially pure alkali metal cyanogencompounds which comprises efi'ecting a reaction in which alkali metalcapable of acting as the base of the cyanogen compound sought, carbonand nitro en participate to form said compound, an separating the latterfrom resi ues of said reaction by distilling said compound under aressure below that at which said compound was formed.

.. The process of preparing pure cyanid comprises effecting a separationof mass by subjecting said mass to a pressure below that oftheatmosphere while in a receptacle the material composing which, at thepoints where the cyanid may encounter the same, is substantiallyincapable of reacting upon the cyanid to deprive it of caron, andvaporizin said cyanid by means of heat while so under reduced pressure.

4. The process of fixing nitrogen which comprises effecting a reactionin successive stages, through the intermediacy of catalytic pate to forman alkali metal cyanogen compound, and removing a ortion at least ofsaid compound from sai catalytic material between said stages whereinsaid reaction takes place.

5. The process of fixing nitrogen which comprises effecting a reactionthrough the intermediacy of catalytic material, in which alkali metal,free nitrogen, and carbon in solution in said material, participate toform an alkali metal cyanogen compound, and removing a portion, atleast, of said compound from said catalytic material, whereby to aid inmaintaining the continued efiiciency of said reactio 6. The process offixing nitrogen which comprises effecting a reaction in stages, throughthe intermediacy of catalytic material, in which alkali metal, freenitrogen, and carbon in solution in said material, participate to forman alkali metal cyanogen compound, and removing a portion, at least, ofsaid compound from said catalytic material betwecntwo of said stages, bydistillation at a temperature below the eutectic poing of said carboncontaining catalytic materia 7. The process of preparing pure cyanogencompounds which comprises effecting a separation of a cyanogen compoundpresent in a mass of material from other constituents of said mass, bysubjecting said mass to a pressure below that of the atmosphere while ina receptacle the material composing which, at the points where saidcompound may encounter the same, is substantially incapable of reactingupon said compound to deprive itof carbon, and vaporizing said compoundby means of heat while so under reduced pressure.

8. The process of preparing pure cyanogen compounds which compriseseffecting a separation of a cyanogen compound present in a mass ofmaterial from other constituents of said mass by vaporizing saidcompound, at an elevated temperature, while in a receptacle the materialcomprising which, at the points where said compound may encounter thesame, is substantially incapable of reacting upon said compound todeprive it of carbon at said temperature.

9. The process of fixing nitrogen which comprises effecting a reaction,through the intermediacy of catalytic material, in which a metal capableof acting as the base of a cyanogen compound, free nitrogen, and carbonin solution in said catalytic material, participate to form a cyanogencompound of said metal, and removing a portion at least of said compoundfrom said material, whereby to aid in maintaining the continued of saidreaction.

10. T e process of fixing atmospheric nitrogen which comprises treatingan alkali metal compound to obtain a vapor therefrom by subjecting saidcompound to heat, reacting upon said vapor substantially simul taneouslywith free nitrogen and with car- 'bon' in solution in a mass ofcatalytic material, to form a cyanogen compound of said alkali metal,and so separating said com- )ound from said catalytic material as toieave the latter substantially unimpaired for continued use.

In testimony whereof I have aflixed my signature, in the presence of twowitnesses.

JOHN E. BUOHER.

Witnesses:

NORMAN E. Hour, HOWARD C. RLPLEY.

